In many industries it is desired to mark products or articles with inscriptions, logos and various designs one of whose functions is to attract the attention of future users or purchasers, for example during presentation in exhibitions.
This problem arises very particularly in the case of rubber articles whose color is black, such as tires or caterpillar tracks.
One way to achieve this is to deposit on the surface of such products a film of a color that contrasts with the black color; that is what is proposed in the patent U.S. Pat. No. 5,904,794 according to which a transfer comprising a colored design is prepared before being applied to the outer surface of a tire blank before its molding and vulcanization. Although this process effectively enables a design of contrasting color certainly to be obtained on the black-colored surface, the design always shows the same color regardless of the orientation chosen for viewing the tire and whatever the direction of the lighting. Products made of black rubber having such a transfer have an attraction power which is not sufficient.
In the case of a tire, the film of color is joined to the rubber of the tire either directly or via an intermediate bonding layer which ensures that the film sticks to the tire. Besides the difficulties of putting this technique into practice, problems can be encountered with it which relate to inadequate bonding between the transfer and the tire, and hence to loss of the said transfer.
In another patent, EP 1152904, a design with several colors is produced on a rubber article by means of a laser which acts on a vulcanized rubber mix of black color in which at least one filler of a color that contrasts with the black is incorporated.
Like the previous process mentioned, this latter one also only allows the formation of a design having the same colors regardless of the orientation along which the rubber article is viewed; besides, it entails incorporating in the material colored fillers which are exposed by laser once the tire has been molded and vulcanized.